1. Field of the Invention
The present invention relates to a zip fastener and, more specifically, to zipper slide for zip fastener, which has means to guide movement of the slide on zipper tapes.
2. Description of the Related Art
FIG. 1 shows a zipper slide constructed according to the prior art. The zipper slide comprises a slide 10a coupled to the interlocking teeth 20a of zipper tapes, a pull tab 11a coupled to the slide 10a for pulling by hand to close/open the interlocking teeth 20a of the zipper tapes. The zipper slide further comprises a spring plate 12a fastened to the slide 10a. The spring plate 12a has a rear retaining portion 13a inserted through a hole in the top wall of the slide 10a and forced by the spring power of the spring plate 12a into engagement with the interlocking teeth 20a of the zipper tapes. When pulling to the pull tab 11a to move the slide 10a, the rear retaining portion 13a is disengaged from the interlocking teeth 20a of the zipper tapes so that the slide 10a can be moved with the pull tab 11a to along the zipper tapes to close/open the interlocking teeth 20a. This structure of zipper slide is still not satisfactory in function. Because the zipper tapes tend to be wrinkled with the fabric of the object in which the zip fastener is installed, the slide 10a may be jammed in the interlocking teeth of the zipper tapes when pulling the pull tab 11a. 
The present invention has been accomplished to provide a zipper slide, which eliminates the aforesaid problem. It is one object of the present invention to provide a zipper slide, which has means to guide movement of the slide on the zipper tapes and to keep the zipper tapes in a smooth manner when pulling the sipper slide to close/open the interlocking teeth of the zipper tapes. To achieve this and other objects of the present invention, the zipper slide comprises a slide, the slide having a top plate and a bottom plate connected in parallel and two sliding ways bilaterally defined between the top plate and the bottom plate, the top plate and the bottom plate each having two horizontal flat extensions bilaterally disposed at one end and adapted to guide movement of the slide on the zipper tapes, the horizontal flat extensions each having front notch disposed at an inner side corresponding to the interlocking teeth of the zipper tapes, and a pull tab coupled to the top plate of the slide for pulling by hand.